1. Field of the Invention
The present invention relates to a general method of inclining a body with small force. The invention also relates to a book rack for use in a study, an office or the like, and to a display rack with which to watch television or the like at any desired angle.
2. Prior Art
A conventional, generally used method of inclining a body includes selecting a particular position as a fulcrum or a rotation axis, and turning the body on the fulcrum or axis.
Bookstands and bookends have conventionally been used to keep books and magazines by ones"" sides for reading, deskwork, etc.
Various methods have been proposed for freely inclining racks or tables which support television sets, computer displays, industrial display terminals, etc. One of the methods includes fitting a bar or arm to a rack, and locking the bar or arm at a desired angle. Another method includes using a spring for balancing with the gravity of an inclining body. Still another method includes elastically coupling a monitor base, which has a spherical bottom, and a set base to each other with an H-shaped post, and sliding the spherical bottom on the set base to tilt the monitor base.
In general it is possible to incline a heavy body with minimum force by turning the body on an axis which extends through the center of gravity, because the body always keeps its balance. In practice, however, it is difficult to do so under circumstances of (about) design or use. Therefore, it is often necessary for a position off the center of gravity to be a fulcrum or a rotation axis. When a body is turned on a fulcrum or an axis off its center of gravity, the center of gravity necessarily changes in height. In order to tilt a heavy body or return the tilted body on such a fulcrum, there is a need of great force for balancing the body against the moment of gravity around the fulcrum. This results in consumption of additional energy which would otherwise not be necessary. Such problems have conventionally been coped with individually. It seems that great interest has not been taken to general methods of reducing the inclining force.
In view of this point, the inventor has studied or considered a general method of inclining a body with minimum force on a fulcrum positioned at the periphery of the body or another position off the center of gravity. This results in the present invention.
An inclining book rack is a thing to which this method is applied for handling books. In general, books are kept upright on bookshelves or in bookstands or between bookends. Soft books, like books with thin covers, magazines and files holding many papers, are apt to bend or fall down on bookshelves etc., so it is difficult for the books to stand. As a result, the bookshelves etc. are apt to be disordered, so books may be difficult to take out from them or put on them. Naturally, books are stabler when laid than when put upright.
Nevertheless, books are kept upright on bookshelves etc. presumably because upright books are easier to take out. In this case, however, the above problem cannot be avoided with regard to soft books.
Not only soft books, but also many books with hard covers, which are easy to handle, are often piled on desks and at nearby places. In this case, to take out a lower one of the piled books, it is necessary to remove the upper ones. Consequently, lower books are less apt to be used.
As stated above, books have such characters that they can be kept more stably if they are piled, while they can be taken out more conveniently if they are kept upright. If books are laid and piled when kept, and if all of the piled books are inclined to be upright when one or more of them are taken out, it is possible to both keep the books stably and take out one or more of them easily. If an apparatus is invented for easily effecting such switching, it would solve all of the above problems. Such a conception is the basis for the present invention as an inclining book rack. The total weight of piled books is fairly heavy, however, even if each of them is light, so it takes considerable force to incline them. Here, it is therefore significant to apply the above general method of inclining a body with minimum force.
Another example of application of this method would be a television rack with which to watch television at an arbitrary angle. As stated above, a television rack or the like may be inclined up and down by various methods. One of the methods includes fitting a bar or arm to a rack, and locking the bar or arm at a desired angle. In this method, however, there is such a limitation that the rack inclination cannot be very large. Another method includes using a spring for balancing with the gravity of an inclining body. In this method, however, the body stability is apt to be insufficient. Still another method includes sliding the spherical bottom of a monitor base on a set base to tilt a monitor. In this method, however, the inclination cannot be very large and the monitor movement is not liable to be smooth.
There seem to be few racks for inclining a television right and left, but it is difficult for a person in a lying posture to watch television. In particular, it is one of a few comforts to a person who is sick in bed to watch television While watching television, the person tries to adjust his/her head angularly to the television screen. As a result, the person""s neck or shoulders are apt to be fatigued unconsciously. In order for a person in a lying natural posture to watch television, it is preferable to be able to adjust the television to the person angularly right and left. To this case also, it is possible to apply the above general method of inclining a body with minimum force.
It s an object of the present invention to provide a method of inclining a body by applying to the body minimum force which is necessary only to transit the body from the condition of equilibrium at an inclination to that at another inclination, in order to incline the body or return the inclined body. In the invention, a body is balanced always even while inclining, and its center of gravity is constant in height. It is possible to determine exactly by calculation the shapes of fulcrum systems for such best body inclination. Therefore, only if the position of the center of gravity can be grasped, desirable fulcrum Systems can be set flexibly without being restricted by the body shape.
A body supported by a plurality of fulcrums are very stable and can be held or fixed at any angle in a stepless manner. Contrariwise, on a body supported by a single fulcrum, there is no friction, and only the roll of the body shifts the fulcrum. It is therefore possible to incline the body with very small force.
It is another object of the invention to provide an inclining book rack which can stably hold even soft books with thin covers, magazines or document files, and from which one or more of the books or the like can be easily taken out. The rack is based on the method of piling up books when holding them, and making them upright when taking out one or more of them. It is easy to take out a lower one of the books piled on the rack. It is possible to return a read book only by placing it on the top of the piled books. It is therefore easy to keep a desk top from being disordered.
It is still another object of the invention to provide a display rack which is highly stable, and which can be held at any stepless angles, by applying the above inclining method. By properly setting fulcrum systems, it is possible to widen the range of inclination. Therefore, a person in a lying natural posture can watch television, without tiring his/her neck or shoulders in an attempt to adjust his/her head angularly to the television screen.
Further objects, characteristics and advantage of the present invention will be clarified in the following explanation.
In order to achieve the above objects, this invention is constructed as follows.
It is one of the characteristics of the invention to incline a body on a fulcrum while shifting the fulcrum. Therefore, the fulcrum part as a whole forms a line or a sequence of points. The fulcrum parts which enable fulcrums to shift as stated above will be referred to as xe2x80x9cfulcrum Systemsxe2x80x9d. The Systems on bodies will be called shifting fulcrum systems, while those on bases will be called fixed (basic) fulcrum systems. In general, the word xe2x80x9cfulcrumxe2x80x9d is associated with a fixed single point. As a little extended concept of this word, however, the word xe2x80x9cfulcrum systemxe2x80x9d will be used herein.
The word xe2x80x9cenvelopexe2x80x9d will be used herein to express the shape of a fixed fulcrum system, which may be not only a curve, but also a sequence of points.
A general method according to the invention for inclining a body placed on a base includes the following. First, a fixed fulcrum system and a shifting fulcrum system are set on the base and the body respectively. A fulcrum is formed by a combination of the fulcrum systems. It is then assumed that the shifting fulcrum system shifts in such a manner as to satisfy the condition of equilibrium and the condition of constancy in potential energy of the body.
The fixed fulcrum system is shaped in the form of the envelope on the shifting fulcrum system in such motion, or in the form of a curve or a sequence of points which is approximate to the envelope. The body is inclined as the fulcrum is shifted. The shifting fulcrum system can move in two ways, according to which the fixed fulcrum system may be shaped in two types respectively. In one of the two cases, there is a fulcrum always on or near the line of action of the gravity of a body. In this case, the shifting and fixed fulcrum systems engage with each other so securely as not to slip. In the other case, a plurality of fulcrums are formed at the same time to support a body. In the latter case, the shifting fulcrum system can slip on the fixed fulcrum system.
An inclining book rack to which the inclining method of the invention is applied includes a book holder and a shifting fulcrum system on the holder.
The holder filled with books corresponds to the body mentioned in regard to the method.
A display rack to which the inclining method is applied includes a table and a shifting fulcrum system on the table. The united body consisting of the table and the display on the table corresponds to the body mentioned regarding the method.
An inclining book rack for inclining piled books is provided in accordance with another method of the invention. The rack comprises a base and a holder. The base includes a pair of outer supports and a middle support between the outer supports. The holder has a bottom and a back. The back is supported by the middle support at a quarter of the height of the holder from the bottom, in such a manner that the holder holding books can freely turn on the support. The outer supports can support the inclined holder.
The operation of the present invention will be explained below.
It can be said that, in general, to incline a heavy body or return an inclined heavy body is to turn the body on a fulcrum or a rotation axis at a particular position on the body by applying to the body a moment of force against the moment of gravity around the fulcrum, so as to vary the body inclination, while balancing the body.
In this case, it can be considered that, in order to incline a body with minimum force, there is a need to satisfy the following two conditions.
First, at every angle to which the body is inclined, equilibrium is reached between the body and fulcrum without any force being applied from the outside (condition of equilibrium). Ideally, the force applied to incline the body should be used merely for the body transition from an angle to another, as the state of equilibrium is maintained. Second, while the body is inclining, the height of its center of gravity is constant (condition of constancy in potential energy). Height fluctuation of the center of gravity requires extra work for it, and therefore needs avoiding.
In solving the task of the invention, it has been the basic policy or line to construct the invention in such a manner as to satisfy the two conditions. In such a case, it is necessary to give attention to the positional relationship between the center of gravity and the fulcrum.
In the construction of the invention where a shifting fulcrum system shifts on a fixed fulcrum system, the contact point between the systems continuously moves, and the fixed fulcrum system becomes the locus of the point, in an ideal condition Therefore, the fixed fulcrum system can be considered to form an envelope for the shifting fulcrum system. Accordingly, the task of the invention of inclining a body on a base with minimum force results in the problem of finding the envelope shape satisfying the above two conditions, as the shape of the fixed fulcrum system on the base which is associated with the shifting fulcrum system set on the body.
As stated later in detail with regard to embodiments of the invention, there can be two cases with regard to such an envelope.
In the first case, the contact point (fulcrum) is positioned on the line of action of the gravity, and the shifting and fixed fulcrum systems engage securely with each other at the contact point in order not to slip (the third embodiment and, analogously, the second embodiment). In this case, while inclining, the body is balanced by the fulcrum always moving just below the center of gravity. This is similar to balancing a rod or the like standing on a hand.
In the second case, the body is supported by a plurality of fulcrums and, contrary to the first case, the shifting fulcrum system can slip on the fixed fulcrum system (the fourth, fifth and sixth embodiments). In this case, while the body is inclining, the resultant force of the vertical reactions at the fulcrums balances with the gravity. At each of the moving fulcrums, in general, a roll and a slip occur at the same time.
In each of the cases, the center of gravity is kept at a constant height.
Thus, in the invention, as a body inclines on a fulcrum, and as its center of gravity moves, the fulcrum synchronously moves. During the inclination and movement, the condition of equilibrium and the condition of constancy in potential energy are satisfied, which are the basic prerequisites for solving the task of the invention. It is therefore possible to incline the body with minimum force. In setting fulcrum systems, only the positional relationship between the center of gravity and each of the systems is the question. Apart from a case where the setting is practically restricted, the setting theoretically has no connection with the body shape.